Blog | Optimal Nutrition For Life

Electrolyte Balance for Endurance

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Ilana Katz MS, RD, CSSD

INTRODUCTION

Sodium is an essential mineral for life. It’s biochemical functions include normal cell function, blood volume regulation, blood pressure/body fluid regulation, pH homeostasis, and heart function. Because sodium in excess can result in increased blood pressure there is a fine line between balancing athletic electrolyte intake to replenish sweat values, and the dietetic recommendations on sodium intake to reduce heart disease.

Most medical organizations recommend low or moderate sodium intake for the general population. Above and beyond the general population, are endurance athletes, whose needs may differ, based on their exceptional loss of sodium through sweat. Sodium ingestion by endurance athletes does not typically increase blood pressure, so low sodium diets are not typically recommended for endurance (and various other athletes too).

I thought it may be useful to outline some alternative points of view for endurance athletes. Note however, although regular physical activity in itself reduces the risk of hypertension, no athletes are immune to hypertension. Furthermore, sodium loss during exercise depends on individual factors, such as genetics, fitness and heat acclimatization, intensity and duration of exercise and the external environment. Athletes, just like everyone else should thus monitor their general health and blood pressure statistics.

Blood Pressure

Statistics are commonly reported in wellness studies that approximately one third of the population may be sensitive to sodium taken in as part of the diet that result in hypertension. The kidney is of primary importance in sodium sensitive hypertension due to its ability to regulate sodium and any dysfunction can cause lead to hypertension .

In healthy people, typical sodium intake does not cause sustained hypertension. Athletes and most normal weight, active people have a lower hypertension risk because studies have consistently shown that blood pressure can be lowered by weight loss and regular aerobic exercise. Moreover, sodium is an essential component of most athletes’ diets because sodium ingestion helps restore total body water and fluid-electrolyte balance by replacing sweat sodium losses.

It is important, however, to note that athletes are not immune to hypertension, and athletes who participate in sports in which large muscle mass and weight lifting are required should monitor blood pressure closely. Sodium intake in this subset of athletes should be considered with the same risks as an inactive person, and be proportional to sweat losses.
Sodium Mechanism

Sodium’s main biochemical functions are the regulation of body water, electrolyte balance and blood pressure which are all connected to the brain for a stimulation of thirst through receptors in the heart known as baroreceptors. Changes in central volume or blood sodium concentration initiate a response including adjustments in thirst and sodium appetite, sympathetic nervous system activity, and renal fluid regulating hormones. In layman’s terms, this means we either get thirsty and/or have salt cravings as required.
Sodium loss during exercise

Sodium loss occurs in most r physical activities, and the duration of the activity further increases sodium losses over time. This loss is exaggerated during exercise in the heat and humidity. Most of the fluid volume loss is a directly related to the sodium lost in sweat. Individuals have varying sweat rates as well as sweat concentrations (the concentration of sodium in the sweat) and the amount of sodium that is lost depends on both of these.

Sweating is related to various factors, such as genetics, diet, body weight, heat acclimatization, fitness levels and other physiological traits, thus there is a wide variation in the amount of sweating and sodium loss among athletes. This variability remains even if all other factors such as the intensity and type of activity are the same and are performed in the same environmental conditions. However, some sodium will be lost during endurance exercise in all athletes and the extent of the loss determines how much sodium needs to be replaced. While some of the sodium released in sweat is reabsorbed by the sweat gland, sweat sodium loss during exercise (especially in the heat) occurs more rapidly than it can be reabsorbed, so much of the sodium in sweat is lost. Heat acclimatization improves sodium (and other electrolyte) reabsorption so heat acclimatized individuals usually have a lighter sweat concentration for any given sweat rate.

Sodium Ingestion for Athletes

Endurance athletes have been known to lose up to 2 – 3% of their weight in an event lasting 2 hours. This can result in about 1.5 to 2g of sodium loss every 90 minutes or so. As both the body water volume is reduced and sodium is lost, an increase in the concentration of sodium in plasma results.

The American College of Sports Medicine position stand “Exercise and Fluid Replacement” provides specific information on the sweat sodium lost during various activities. Although there is wide variation across individuals and activities, this position stand indicates that athletes can lose as much as 5 g sodium in sweat during a single high intensity workout. Thus, during endurance exercise, the sodium ingestion plays an important role to minimize dehydration and assist with body fluid maintenance and electrolyte balance. Sodium ingestion not only replaces some of the sodium lost in sweat, but induces the thirst drive to aid the athlete to continue drinking and increase fluid consumption. To kill two birds with one stone per se, the athlete should use sports drinks with sodium concentrations that are formulated to match their sweat rate, or supplement their fluid intake with salt tablets or electrolyte supplements if their sweat is typically highly concentrated.

Thirst

Body water volume restoration is assisted by hormones and baroreceptors that initiate a thirst sensation. Fortunately, the thirst sensation is extremely sensitive to changes in sodium within the blood, and as little as a 2% change will induce thirst. These thirst mechanisms during endurance exercise are most effective for training or events under two hour typically. They tend to desensitize after longer periods of time due to a number of other factors offering interference with the thirst mechanism over time. For example, the mere act of swallowing suppresses the thirst sensation.

To optimize performance in longer events, athletes should therefore have a liquid intake strategy that includes a sodium replacement element.

Endurance Associated Hyponatremia (salt levels too low)

As noted earlier, a ~ 2-3% loss in total body water with a simultaneous increase in plasma sodium concentration is fairly common for marathoners. Unfortunately this condition is one of the highest causes of death in endurance sports, and therefore these facts should be carefully noted, particularly by athletes. Athletic hyponatremia is associated with several serious symptoms, such as confusion, nausea, light-headedness, dizziness and fatigue In severe cases, the consequences of brain swelling can cause permanent damage from which some athletes do not recover.

The best way to avoid the risk is to be sure that fluid intake does not greatly exceed fluid loss. Athletes can track this by monitoring fluid intake as well as the volume and concentration (color) of urine.

Unfortuanetly, mechanisms contributing to endurance associated hyponatremia have been difficult to study because most investigations in the area are retrospective: that is, athletes who have become hyponatremic during a long distance event are already at the finish line, or receiving treatment in medical tents. These studies have their limitations in that they may miss subjects with who are asymptomatic and recover on their own. The studies available therefore are only regarding extreme cases or athletes who are more sensitive to hyponatremia and experience symptoms with only small changes in plasma sodium.
PRACTICAL APPLICATIONS

There is large individual variability across athletes and/or active people in sodium losses through sweating, so athletes should evaluate sodium and fluid losses during workouts.
Athletes should practice their fluid replenishment strategies as they are training for the event, and learn which products will be provided by the race organizers along the route. They should have a good idea of what provides optimal sodium for their levels (drinks, snacks, etc.) in case those at the race need to be supplemented with their own stash.
Combining urine examination to determine how dark or light the urine is with measurement of a usual body weight can provide an indication of any significant changes in hydration status.
Sodium ingestion during long term exercise

- improves hydration through volume retention
- increases plasma sodium content
- maintains thirst for reminder signals
- stimulates the kidneys to retain water

One liter (34 oz) of a well designed sports drink will typically provide 460 mg of sodium.
Although body fluid status related to dehydration and endurance associated hyponatremia (often a result of excessive drinking) is completely different, some of the symptoms, such as confusion, nausea, light-headedness, dizziness and fatigue can overlap. Therefore, if changes in body weight or a blood sample cannot be attained, assessment of fluid intake and urination during the (training) event is important before deciding on treatment.
Athletes who lose large volumes of sweat should consider supplementing additional sodium in the form of sports drinks with greater sodium content or bars, gels, electrolyte powders/tablets, or salty snacks that provide extra sodium.
Many sports drinks are hypotonic to blood plasma (has a lower salt concentration to blood plasma,) so athletes who use sports drinks should not assume that they are immune hyponatremia.

SUMMARY

Thirst, drinking and hormonal regulation of fluid balance are tightly controlled through homeostatis. Blood plasma sodium concentration is a potent thirst stimulus at rest, during exercise and in the post-exercise rehydration period. Sodium ingestion is a recommended means to continue a thirst inducing drive to ensure adequate rehydration.

The sodium can come as a part of the athlete’s diet, but after long lasting endurance exercise, especially in the heat, the athlete may want to consider salty snacks or drinks with electrolytes. Sodium ingestion and maintenance of sodium concentration also stimulates renal mechanisms to reduce water loss in urine and conserve fluid.

SEPTEMBER 2023 NEWSLETTER

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September is a tribute to our neighbors south of us. Mexico is a country with very beautifully rich history, from its people to…well it’s food. Mexican food is a mainstay for Americans but it can be very rich in calories, fat & sugars. Here are some ideas to both enjoy the wonderful cuisine while staying healthy…Enjoy!

Cinnamon Up Your Life

Cinnamon is a very common spice used in Mexican cuisine. There have been many studies discovering the many possible benefits of cinnamon such as: glucose metabolism, antiseptic powers against bacteria’s and fungi and even for improving brain function.

Some of the possible ways in which one can enjoy this power spice:

– Add a cinnamon stick to flavor your favorite tea

– Add to unsweetened applesauce, cereal or oatmeal

– Sprinkle on toast or add to butter or cream cheese

– Sprinkle on coffee, cocoa, fruit juices, and ciders

– Add cinnamon to your favorite baked goods

Remember after opening your cinnamon store it in a tight sealed container away from the light.

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Colorful Bean Salad

INGREDIENTS

16 ounces garbanzo beans, canned
16 ounces kidney beans, canned
16 ounces black beans, canned
16 ounces corn, canned
2 tablespoon apple cider vinegar
1 tablespoon extra virgin olive oil
2 ounces roasted red bell pepper, from a jar, diced
6 ounces green bell pepper, seeded, small dice
2 tablespoons cilantro, fine chop
1 tablespoon Italian parsley, fine chop

METHOD

* Rinse and drain all canned items. In a large bowl, combine all ingredients. Chill before serving for 15-20 minutes.

Servings: 16

Per ¾ cup serving: Calories: 130 calories, Fat: 2g Carbs: 24g Pro 4g

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Rice Pudding

INGREDIENTS

1 cup brown rice
3 cups water
12 ounces evaporated milk, non fat
3 tablespoons condensed milk, low fat
2 ounces raisins
1 teaspoon ground cinnamon

METHOD

In a medium saucepan, combine rice, and water. Cook over low heat, covered, for 13 minutes, until tender. Add evaporated milk and condensed milk and raisins. Stir well . Cook 8-10 minutes. Rice should be moist, liquid (milk) should not be completely dry. Serve in individual plates. Garnish by sprinkling with cinnamon.

Makes 4 cups, 16 Servings

Per serving OF 1/2 cup each: Cals: 160 Fat: 1.5g Carbs: 25g Pro: 7g

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Cilantro…the Aphrodisiac

When speaking of spices & herbs, I would be remised to not mention this staple herb, thought to be an aphrodisiac and have healing properties, and adds great flavor to a variety of foods. It looks like parsley and is best when fresh. Here are some ways to enjoy it: use cilantro leaves instead of basil in tomato-mozarella salad, sprinkle 1tbsp chopped cilantro over scrambled eggs, add a few leaves to grilled cheese sandwiches, garnish Bloody Mary’s with a whole sprig or two, use in marinades for chicken, fish, shellfish, lamb, and pork.

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Summer Fruits

The great thing about Mexico is the availability and use of wonderfully refreshing fruits. Fruits are packed with vitamins, fiber, antioxidants and will help hydrate to keep you looking young and feeling good. For fun, healthy treats for the whole family, try:

Adding sliced citrus fruits like lemon, lime, or orange to your water
making ice cubes from fruit juice rather than reaching for a soda.
Adding sliced berries or a banana to your cereal or waffle for a refreshing summer breakfast.
Adding fruits such as mangoes and berries to your salad for a sweet summer flavor.
Serve fresh fruits for dessert which are just as sweet but lower in fat than cakes and ice cream

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Mexico Fun Fact

Generally, Mexican food follows tips and instructions form Aztec recipes, which have been handed down

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FITNESS CORNER:

For this segment I am emphasizing Recovery Nutrition:

The body stores carbohydrates, in the form of glycogen, in very limited amounts. It is thus important to maximize that storage capacity, to prevent the risk of running out of energy before the training session is over.

The enzyme responsible for storing glycogen is elevated after exercise. It is elevated within 30 minutes post-exercise, but remains above normal levels up to 24 hours later. It is therefore vital to take in an adequate amount of carbohydrates as soon after exercise as possible. Adding some protein to that meal or snack will not only enhance glycogen storage capacity, but it will also aid in muscle recovery.

The following calculation can be used to figure out how much is an adequate amount of carbohydrate to consume after your intense workouts.

Body Weight (lb.) x .5 g/lb = _____ g of Carbohydrate

example Athlete is 140 lbs ::: 140 lb x .5 g/lb

= ~ 70 g of carbohydrate is required for recovery

To facilitate glycogen resynthesis as well as muscle recovery eat a ratio of approximately 3:1 or 4:1 carbs to protein. So once you calculate how many grams of carbs you need for recovery, you can figure your protein needs by dividing by 3.

A great idea:

Ezekiel English muffin with an egg soufflé

(lets call it Huevos Ilanos in honour of our Mexican theme)

Method:

Spray a muffin tray with Pam. In each section pour about 3 oz of egg whites (1 egg white = 1 oz). Add in some cut up veggies of choice, such as peppers, spnach, mushrooms. Add some salt and pepper to taste, and sprinkle with a little parmesan cheese (optional).

Bake at 350 degrees for approx 30 – 35 minutes (until eggs are set). Each egg soufflé is about 16g of protein. The English Muffin is about 30g of carbs, so with a side of fruit, this would make a perfect recovery meal from a hard work out.

Have a healthy month!!

ILANA

Counteracting Muscle Glycogen Depletion

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Because Low carbs is all the rave right now, I felt an article about Carbs for athletes (particularly endurance) is timely.

Carbohydrate is typically the limiting energy substrate in exercise, meaning that it will run out before protein or fat runs out. Glycogen depletion is a term used to describe when carbohydrates are used up and no longer exist as a fuel source for working muscles. In other words energy stores are depleted, which can result in cells and muscle tissue being damaged and the immune system being stressed if exercise continues. Some of theses metabolic processes, which can lead to muscle soreness and damage, can be counteracted to a degree by dietary factors.

What and How Much should I eat

Before the workout

It is important to fuel your muscles before the workout begins. A good analogy to remember is that you do not drive your car to its destination, and then put gas in it – our bodies work the same way. Fill the tank by eating a meal comprising mostly of low- to moderate-glycemic carbohydrates two to three hours before exercise (e.g. oatmeal). A good preworkout meal should contain some protein, which in turn decreases the body’s reliance on muscle protein as an energy source, sparing the muscle to focus on the workout. It also enhances the recovery period by being available as amino acids for protein synthesis (e.g. add a scoop of whey protein powder to the oatmeal).

During the workout

The aim is to increase sparing of muscle glycogen and simultaneously improve endurance. Maintaining a continuous source of glycogen during intense training minimizes muscle tissue damage and further aid in post-workout recovery. There is consensus that 8 to 10g of carbohydrate per kg of body weight will maintain appropriate glycogen levels during heavy training. Recommendations for an endurance event include liquid carbohydrate right before the event, and a regular consumption of glucose polymers (e.g. maltodextrin) during the event, to delay fatigue. A 6 to 8% solution containing 15 to 20g of carbohydrate per 7oz of water is ideal (such as Gatorade or Powerade). Such sports drinks are easily absorbed during workouts, as well as provide water and electrolytes to prevent dehydration. New research shows that in addition to the glucose intake, a small amount of protein during workouts may also stimulate more insulin, which further aids the transportation of glucose to the muscles. Amount of appropriate consumption will depend on the type of athlete, the intensity and duration of the event, and the temperature.

After the workout

A first priority after a workout should be recovery in order to return to be fully prepared with a full tank of fuel for the next training bout, as quickly as possible. It is not possible to consume enough carbohydrate during moderate- to high-intensity exercise to replace the glycogen that has been depleted. Furthermore, the muscle degradation during exercise requires protein to fully recover. It is therefore important to consume additional carbohydrate and protein after the workout. This should be done as soon as possible, a period known as “the muscle recovery window” or “the glycogen replacement window” (the first two hours after exercise). This is because the enzyme (glycogen synthase) responsible for storing glycogen is highly elevated immediately after exercise. Again, a combination of carbohydrate and protein is the best source of macronutrients for post exercise recovery. Sports drinks are highly recommended for the recovery period due to their ability of rapid absorption, and their water and electrolyte content.

Consequences of unrecovered glycogen depletion

Failure to appropriately replete glycogen may result in chronic glycogen depletion. There is evidence linking muscle glycogen depletion with both fatigue and injury. Symptoms are very similar to those of over-training. Muscles that are fatigued lose their strength, and thus their ability to protect joints, with the unfortunate risk of injury. The purpose of a good recovery nutrition strategy is to avoid chronic glycogen depletion that can take place over several days of training and avoid injury. Furthermore, consistency in glycogen repletion results in effective and recovery between workouts and competitions and thus overall improved performance during competition.

Tips to avoid gastrointestinal distress for training/racing

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Ilana Katz MS, RD, CSSD

If you think you are alone when your first focus for any race is gastrointestinal distress, you are not. Are you always plotting your day based on where the bathrooms are going to be (even the ones along the course), or always having to get to races early knowing that you will be standing in the line multiple times, and do you plan your training days around where the pit stops have to be. Believe it or not, athletic GI distress affects more than 60% of athletes.

Some of the reasons include pre-race anxiety, eating a bigger than normal breakfast in anticipation of extra fuel requirements, and then the all too familiar jostling stomach and intestines experienced in any sport that includes ground reaction forces (particularly running).

Hopefully these tips can shed some light onto your individual struggles and help reduce your stomach troubles.

Prone to the jostle…

You may be surprised about this one but often something tight around your waist may help prevent organs from jostling. I personally discovered this one when my own GI issues were reduced after investing in a fairly tight fuel belt. On race day, the race belt used to pin race numbers too can also assist in this cause. Now of course this is hit or miss, and may just be a band-aid to a deeper problem, therefore always record fuel and fluid consumption for every training and racing day, noting all the specifics, like weather, humidity, pre-exercise meal, etc., Detailed data can often uncover the triggers for side stitches, onset of diarrhea or nausea, and the like. Data helps create optimal solutions and some slight dietary tweaks during the days and weeks leading up to events will eventually have zero-runs runs.

Understand your individual transit time

Dreaded diarrhea is a major concern for many athletes, as mentioned above. The jostle reduces blood flow to the intestines which is more likely diverted to the exercising muscles. With reduced blood flow when needed, the intestinal hormones may get thrown off balance and this in turn will quicken the transit time (what is clinically called the gastric emptying rate). Many athletes in the early phase of their fitness journeys unaccustomed to stress of hard and intensified exercise are more likely to experience runners’ trots. As the body adjusts, intestines will revert to their normal bowel patterns and ease up this syndrome. However, not always… unfortunately even experienced athletes may experience the dreaded liquid stomach especially if there are pre-existing gastric concerns, various intolerances and allergies, and irritable bowel syndrome.

These tips may help:

Warm up before a race day or an intense training day. Exercising lightly stimulates the bowels to empty.
Adjust training times to different times of the day to help understand your transit time better. For early morning, try drink something hot like coffee, hot lemon water, tea, etc., but be sure to allow for time to sit on the thrown with patience.
Find stress reducing exercises for race day with the goal of reducing anxiety and fretting. Many sports psychologists suggest meditation, breathing exercises, yoga poses and practicing positive visualization of a stress free environment.
Eliminate high fibrous foods the day leading up to the race, and especially the morning of. Fiber increases transit time and usually at a very inconvenient time when racing.
Do not chew gum or drink carbonated beverages or anything else that either causes the swallowing of air or the popping of air bubbles intestinally.
Sugar-free products that contain sugar alcohols are even more the devil than one would think. Sorbitol (found in many sugar-free gums and processed products) is a stimulant for the onset of diarrhea.

An interesting way of getting to the bottom of your personal transit time is to eat and monitor elimination with foods that are visible in the feces like corn, pumpkin or sesame seeds, or beets (based on color changes).

Hydrate consistently and well

Often diarrhea is related to dehydration, and moreover, exercise-induced dehydration – which is related to sweating out more fluid than is optimally comfortable replacing. Athletes are too quick to blame the ingredients in many of the available sports nutrition products. This means hydration each and every day, not just days before a race, or race day itself.

Eliminate suspected culprits

We typically know our own bodies and suspect various foods that may be contributing factors. For a week, eliminate any suspicious foods such as coffee, dried fruits, beans, high fiber breads or cereals, dairy-based foods and whatever else you feel is necessary. Next, eat a bigger than usual dose of the one suspected food and observe. Typically changes in bowel movements provide the best answers. If your GI symptoms reduce when you cut out dried fruit for example, but have a worrisome situation when you then eat an extra-large portion, the answer becomes obvious: don’t eat dried fruit.

Do not forget to investigate medications’ possible side effects

More than often, athletes forget to incorporate any pharmaceuticals or even over the counter supplements they may be taking into the equation. If all else fails, consult with your doctors, especially if you are on medications for any reason (even the reason may become symptomatic during races.) Furthermore, doctors may be able to suggest anti-diarrheal ideas such as Imodium to help.

In summary

Races can be won or lost at the porta john. Although many athletes experience gastrointestinal difficulties, it is an individual struggle with an individual solution. Hopefully some of these tips can reduce the frustration of your bathroom issues and prevent a derail of your perfect training regimen on race day. But to genuinely help yourself, start a food and distress log which may help eliminate suspicious culprits.

Eat to beat Cramps

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The physiology of cramps can be complex. Nutrition may or may not have a role to play behind the why!!

Stretching out and massaging muscles can certainly be a good start but this is often NOT enough, since electrolyte balance plays a major role in muscle function and recovery.

Key nutrients include sodium, potassium, magnesium, chloride and calcium.

On a personal level, having participated in master’s swim meet, while training for Ironman races, it is not uncommon for me to observe swimmers gathering at the lanes end in-between sets to mention their cramps. It amazes me how everyone in the pool suddenly becomes a nutritionist, and I bet you can guess which foods they suggest?

Did you have a banana in your thought processing just then? (well you are not alone) – as most of us know, bananas are a good source of potassium. Interestingly enough, they also have a decent source of magnesium and calcium. Its no wonder most of you would be right about recommending a banana at the side of the pool…. But, there may be the fine line between some other factors as to whether bananas may eliminate the cramps, or in fact preserve the cramp.

Did all you swimming nutritionists consider some very important physiology of sweat and muscle movement. What else may play a role?

– Hydration

– Supplementation

– Intensity and duration and type of exercise/training

– Medication side effects (probably the one you would want a professional to chime in on)

Why wait for the why, why not avoid the onset? Or at very least, fix the problem rather than exacerbate it.

TRAIN STRONG,

ILANA